Electric switches



Oct. 6, 1959 R. P. BALLcu 2,907,856

v ELECTRIC SWITCHES Original Filed Sept. 26, 1950 INVENTOR. Ra/5am F,5a/fau YfoluN M h @d-ZL @L .ATTORNEYS ELECTRIC SWITCHES Richard `P.Ballon, Hartford, Conn., assignor to Federal A,

Pacific Electric Company, a corporation of Delaware Original applicationSeptember 26, 1950, Serial No.

186,857, now Patent No. 2,747,060, dated May 22, 1956. Divided and thisapplication October 26, 1955, Serial No. 546,365

14 Claims. (Cl. 200-170) This invention relates to electric switches andmore particularly to switches of the knife-blade type.

In the enclosed or safety type switch having a quick make and breakmechanism, for example, and not by Way of limitation, a mechanism asshown in the copending application of T. M. Cole and P.-M. Christensen,Ser. No. 144,63 6, iiled February 17, 1950, now Patent No. 2,760,021,issued August 21, 1956 and assigned to the `assignee hereof, the switchaction is effected by spring energy. This energy is produced by thepreliminary m07 tion of an external switch handle and serves to open theswitch blade with a snap action. In the smallerswitches, the completemovement of the switch blade may be effected by the spring energy, butin larger switches this energy is vusually too large and i-t iscustomary to have the external switch handle rst compress the spring andthen break the engagement of the blade and the stationary contact bydirect mechanical linkage, after which the spring snaps the blade to itsfull open position.l However, on closing the switch the spring must bestrong enough to move the blade through its complete arc for rmengagement with the stationary contact.` As the handle throw is limited,and the spring energy must be produced in only a portion of the throw,in both the On and Off `direction thereof, the Iforce required to throwthe handle may reach an excessive value unless the friction internallyof the enclosure is kept low. In actual practice, such handle forces arehigh. However, if the energy required to move the switch blade through asubstantial portion of its arc of movement can be materially reduced,less force is required to operate the handle and Fatented Oct; 6,` 19592 The above and other objects, features and advantages of the presentinvention will be more fully understood from the following descriptionconsidered in connection with the accompanying illustrative drawings.

In the drawings: Fig. 1 is aside view, in elevation, illustrating adoubleblade knife switch embodying the present invention, theV switchbeing closed;

Fig. 2 is an end View, as seen from the arrow 2 1n Fig. l;

Fig. 3 is a sectional view taken Yon 'line 3-3 of Fig. 1; Figs. 4, 5 and6 yare 4views similar 'to Fig. 3, with por- 'tions removed, showingmodifications; and

Fig. 7 is a lfragmentary view similar to Fig. 3, showing anothermodification.

Referring now to Figs. l, 2 and 3 in detail, there is shown aknife-blade switch 10 embodying the present invention, comprising aninsulation base 11,'a stationary contact or rupture member 12 bevelledas at 13 and connected to a terminal member 14, yand a movablebladecontact member 16 which is pivotally connected to the terminalstudor hinge contact 18. The latter tapers in thickness as indicated at 19(Fig. 3), for a purpose which Awill presently appear. The moi/able bladecontact member 16 comprises the resilient metal strips 20 and 22 whichare flared outwardly at the rupture ends thereof, as indif cated at 24.Said blades are pivotally mounted on the .stud 18 by a rivet 25 which isof greater longitudinal extent than the combined thicknesses of theblades and the stud so that the heads 27 of the rivet 25 are spaced fromthe adjacent blade surfaces, respectively, in the closed condition ofthe switch, as illustrated in Fig. 3. In order to provide the requiredContact pressure at bo-th ends of contact member 16, a bolt 26 extendsthrough the aligned apertures 28, 28 in each of the strips 20 and 22, itbeing noted that the ydiameter of the bolt is smaller than the an easieroperating switch will be produced. Since heatf' ing can occur at boththe hinged and the rupture ends of the switch blade, adequate Contactpressure must be provided at both ends. With the current the same atboth ends of the blade, and since the hinge and rupture posts -aresimilar-conducting members, the contact pressure the contact pressure-at the hinged end although it may change the ratio of said contactpressures. l

- Therefore, the primary object of the present invention is theprovision of a switch which requires substantially less effort forhandle operation than in the prior art.

Another object is the provision of a switch blade ha'ving adequatecontact pressure -at b oth the hinged andrup-4 ture ends thereof in theclosed condition of the switch, the pressure at the hinged end beingsubstantially reduced A at the moment of disengagement of the ruptureend,` vso that very little eiort is then required to move the blade..

to the full Olf position thereof.

diameter of said openings to provide for relative movement of saidstrips and the bolt. A compression spring 30 is mounted on the bolt, oneend of said spring bearing against the outer surface of strip 20 and theother end of said spring bearing against a nut 32 on the bolt. A locknut34 is threaded on the end of the bol-t. As a result of thisconstruction, the strips 20, 22 of the blade-contact 16 may be adjustedto provide the required resilient contact pressure against thestationary Contact 12 and the stud or hinge contact18. The spring 30 ischaracterized by a high spring constant so that a small change in the.compression thereof will cause a much larger change in the operatingmember may be positioned -above'the movable contact member rather thanbelow the movable contact member, as here shown. Although the presentinvention l is applicable to various different types of switches, itisintended primarily for use in a switch operated by a quick make andbreak operating mechanism such as for example, that illustrated anddescribed in the above mentioned copending application of T. M. Cole andP.

Christensen, said mechanism operating a bail which engages the operatingmember of the switch. v

When the switch is opened, by moving the blade-contact `member 176 so asto disengage the llared portions 24 n'thereof from the stationarycontact 12, the spring 30,Y

which is compressed in the closed or circuit making con- Akdition of theswitch, is -free to expand immediately uppn said disengagement. Theexpansion of the spring causes the ystrips and v22 to collapse towardeach other and, due to the high spring constant, a slight expansion onlyresults in the dissipation of the spring energy whereupon the pressurebetween the pivoted ends of said strips and .the stud18-is.relieved,said ends being permitted to .move .freely in the spacebetween rivet 'heads 27 and the stud 18, bevelled edge 19 aiding this.movement Therefore, it will be apparent that any further rotarylmovement of the blade contact 16, after it disengages the stationarycontact 12, to .the full Ofi position thereof may be .achieved ywithvery little friction at the pivoted end thereof. It will be noted thatthe bevel 13 at the free -end of contact 12 permits it to be readilyVre-engaged by the flared ends of contact 16 when the latter is moved tothe vclosed ,position thereof.

In Vthe modification illustrated in Fig. 4, the combination of the boltv26 and the -helical spring 3i) is replaced by la rivet 4t) which passes-loosely through the aligned openings 28 in the strips 20 and 22 andwith the hat strip `spring member 42 which is engaged .between one endof :the rivet it? andone of the blades of the movable contact, hereshown as the blade 22. .It will be noted that the spring 42 extendslongitudinally of the .movable :contact member, one end 'of the springbeing adjacent the .ared end, .for applying contact pressure when said.end .engages thestationary contact 12, and the other end of said springbeing .adjacent the pivoted end of the .movable contact .member forapplying contact pressure ,at the stud 18. Spring 42 is alsocharacterized by-a yhigh spring constant, said spring being tensioned inthe closed condition of the switch. It -will be understood that when themovable contact member 16 disengages the stationary contact/12, vspring42 will be effective to cause the blades thereof to :collapse towardeach other7 in the same manner as helical spring 3i), thereby relievingthe contact pressure at kthe stud, as previously described, so that themovable contact member can oe carried to the full Off position thereof-with very little friction.

ln the modification illustrated in Fig. 5, the spring is completelydispensed with. In said modification the-rivet 44 extends through thealigned openings 28 infeach ofthe individual blades, said rivet having aloose lit therein and the shank thereof being slightly shorter than -theycorn- =bined thickness of contact 12 and both blades, so that saidblades are bowed inwardly when the switch is closed and thereby providetheir own pressure on both `the stationary contact 12 and the stud 18.The switch will opervate substantially in the same manner as previouslydescribed so that when the blades disengage the stationary contact theycollapse toward each other and the contact -pressure is relieved at thepivoted end thereof.

In the modification illustrated in Fig. 6, a `threaded bolt 46 and a nut48 are used in place of the rivet 44 so ythat the switch can be adjustedto the desired pressure regardless 'of manufacturing variations. Theswitch so modified operates in the same manner as the switch of Fig. 5.

It will be noted that in each of Figs. l through 6, the stud 18 istapered at 19 on the edge portion thereof which confronts the stationarycontact 12. As previously described, this serves to aid the collapse ofthe blades when they disengage the stationary contact 12. As shown inFig. 7, in order to provide for the collapse of the blades with lessclearance between the heads 27 of rivet 25 .and the adjacent bladesurfaces, the stud 18 is provided with an arcuate contour at theopposite sides 52, 53, thereof, and the adjacent ends of the blades arecurved inwardly, as at 54, to conform to said contour.

In each of the embodiments of Figs. 1 6, a restraining member 26, 40, 44or 46 extends loosely through both contact blades about midway betweenthe ends .of those blades and parallel'to the pivot 25, as shown, therestraining-member in each case having an abutment inthe form of`aflieadoranut that confronts one "of the blades. lIn

4 most instances the abutment .acts Adirectly against .the blade but inFigs. 3 and 4 a spring is interposed between the blade and itsconfronting screw head or rivet head. In each embodiment, whether theblades are relied on for resiliency or whether the coil spring 30 or theleaf spring 42 provides this property, there is a resilient contactpressure developed at both sides of'each stud 12 and 18 upon closing ofthe switch. In Figs. 3 and 4, the resilient pressure applied directly toone switch blade by the spring reacts via the restraining 'screwor rivetand thusapplies resilient pressure indirectly to the -midpoint of theother blade. In this way, a single spring develops .contact pressure byboth blades against both sides of each contact ,stud as is fof coursetrue, too, of the embodiments in Figs.

5 and 6 where the blades, restrained by a member loosely extendingperpendicularly through the blades, develop Contact pressure againstboth sides of each contact stud.

This is a division of my copending application Serial No. 186,857, tiledSeptember 26, 1950, now Patent 2,747,- O60, issued May 22, 1956.

While I have shown and described Ithe preferred e-mbodiments of myinvention, it will be understood that various changes may be made in thepresent invention without departnig from the underlying idea orprinciples .of the invention within the-scope of the appended claims.

Having thus described my invention, what I claim and desire to secure byLetters Patent, is:

fl. In an electric switch having a terminal stud, astationary contactstud and a movable switch contact blade having -laterally spacedrelatively movable parts disposed at opposite sides respectively of saidterminal stud and pivotally mounted .thereon for releaseable engagementwith 'the respective opposite sides of said stationary `contact stud,and means carried by said switch contactblade `for restraining saidrelatively movable parts against separation beyond their lateral spacingas aforesaid, said means including an element engagingat least one ofsaid relatively movable parts intermediate the ends thereof andaccommodating lateral movement of said parts towards each other as wellas exing of one or both of said parts as may be engaged by saidrestraining element, said movable switch contact blade and `saidrestraining means `including resilient means for biasing said parts intocontact- -pressure engagement with the respective sides of both saidstuds in the engaged condition of said contact blade with saidstationary contact stud, said resilient means being proportioned forrelease of said contact pressure of said parts against said terminalstud as the `direct result of said relatively movable parts bringremoved from said stationary contact stud and said parts being therebyfreed to move relatively toward each other.

-ried by said contact blade forrurging said parts into contact-pressureengagement with the adjacent sides, respectively, of both of said studsin the engaged condition of said contact blade, said means beingoperative, upon disengagement of said contact blade from said stationarycontact stud, to effect mutual relative movement of said parts formoving the latter out of contact-pressure engagement with said terminalstud, said means being spring means having a high spring constantwhereby the spring pressure on said blade is substantially dissipatedupon said mutual relative movement.

3. In an electric switch having a terminal stud, a stationary contactstud, a movable switch contact blade having laterally spaced relativelymovable parts disposed at 'opposite sides respectively of'said terminalstud, and pivot means yextending through said parts and said terminalstud mounting saidparts for movement to and vfrom engagement at oppositesides of said stationary contact, 'respectively, said pivot means havinga head portion Yat each endV thereof which is spaced from the adjacentpart minal stud, means carried by said contact blade for urging saidparts into contact-pressure engagement with the adjacent sides,respectively, of both of said studs inthe engaged condition of saidcontact blade, sai-d inens being when the latter is in contactengagement with said teroperative upon disengagement of said contactblade from said stationary contact stud to eifect mutual relativemovement of said parts for moving the latter out of contact-pressureengagement with said terminal stud.

4. In an electric switch having a terminal stud, a stationary contactstud, a movable switch contact blade having laterally spaced relativelymovable parts disposed at opposite sides respectively of said terminalstud, and pivot means extending through said parts and said terminalstud mounting said parts for movement to and from engagegA ment atopposite sides of said stationary contact, respectively, said pivotmeans having a .head portion yat each end thereof which is spaced fromthe adjacent part When the latter is in contact with said terminal stud,means carried by said contact blade for urging said parts intocontact-pressure engagement with the adjacent sides, re-

Ving laterally spaced relatively movable parts disposed at oppositesides respectively of said terminal stud, and pivot means extendingthrough said parts and said terminal stud mounting said parts formovement to and from engagement at opposite sides of said stationarycontact, respectively, said pivot means having a head portion at eachend thereof which is spaced from the adjacent part when the latter is incontact engagement with said terminal stud, means carried by saidcontact blade for urging said parts into contact-pressure engagementwith the adjacent sides, respectively, of both of said studs in theengaged condition of said contact blade, said means being operative upondisengagement of said contact blade from said stationary contact stud toeffect mutual relative movement of said parts for moving the latter outof contactpressure engagement with said terminal stud, said terminalstud being tapered at the marginal edge thereof facing outwardly of saidblade and the adjacent portions of said parts being provided with acontour complementary to said taper.

6. In an electric switch having a terminal stud, a stationary contactstud, and a movable switch contact blade having laterally spacedrelatively movable parts disposed at opposite sides respectively of saidterminal stud and pivotally mounted thereon for releasable Aengagementat opposite sides of said stationary contact stud, means carried by saidcontact blade for urging said parts into contact-pressure engagementwith the adjacent sides, respectively, of both of said studs in theengaged condition of said contact blade, said means being operative upondisengagement of said contact blade from said stationary contact stud toeffect mutual relative movement of said parts for moving the latter outof contact-pressure engagement with said terminal stud, said parts beingformed of resilient material, and said means being a member extendingloosely through said parts intermediate the outer ends thereof andprovided with a head portion at each end thereof in contact with theouter surface of the adjacent part, said member being dimensioned toretain said parts in resilient engagement with both of said studs invsaid engaged condition of said blade, said parts being freed formovement toward each other along said member upon said disengagement ofsaid blade to relative the contact pressure thereof at said terminalstud.

7. In an electric switch having a terminal stud, a statit-)nary contactstud, and a movable switch contact `blade having laterally spacedrelatively movable parts disposed at opposite sides respectively of saidterminal stud and pivotally mounted thereon for releasable engagement atopposite sides` of said stationary contact stud, means carried by saidcontact blade for urging said parts into contact-pressure engagementwith the adjacent sides, respectively, of both of said studs in theengaged condition of said contact blade, said means being operative upondisengagement of said contact blade from said stationary contact stud toeifect mutual relative movement of vsaid parts for moving the latter outof contact-pressure engagement with said terminal stud, lsaid partsbeing formed of resilient material, and said means being a member eX-tending loosely through said parts intermediate the outer ends thereofand provided with a head portion at each end thereof in Contact with theouter surface of the adjacent part, said member being dimensioned toretain said parts in resilient engagement with both of said studs insaid engaged condition of said blade, said parts being freed `formovement toward each other along said member upon said disengagement ofsaid blade to relieve the contact pressure thereof at said terminalstud, one of said head portions being adjustable longitudinally of saidmember for adjusting the contact pressures ofsaid blade.

- 8. In an electric switch, a terminal contact stud and arupture'contact stud spaced therefrom, a pair of contact bladespivotally mounted at one end thereof on said terminal stud in contactwith the opposite sides, respectively, of said terminal stud forreleasable contact engagement at the other end thereof with the oppositesides respectively, of said rupture stud, said blades being free toconverge at said other end thereof when disengaged from said rupturestud, and means operable to limit the separation of said blades uponengagement thereof with said rupture contact.

9. In an electric switch, a terminal contact stud and a rupture contactstud spaced therefrom, a pair of contact blades pivotally mounted at oneend thereof on said terminal stud in contact with the opposite sides,respectively, of said terminal stud for releasable contact engagement atthe other end thereof with the opposite sides respectively, of saidrupture stud, said blades being free to converge at said other endthereof when disengaged from said rupture stud, Iand means operable tolimit the separation of said blades upon engagement thereof with saidrupture contact, and means operable to provide contact pressure betweensaid blades and said studs when said blades are in contact with saidrupture stud.

l0. In an electric switch, a terminal contact stud and a rupture contactstud spaced therefrom, a pair of contact blades pivotally mounted at oneend thereof on said terminal stud in Contact with the opposite sides,respectively of said terminal stud for releasable contact engage/ment atthe other end thereof with the opposite sides, respectively, of saidrupture stud, said blades being free to converge at said other endthereof when disengaged from said rupture stud, means interengaging saidblades between the ends thereof to limit the separation thereof uponengagement with said rupture contact, and resilient means operable uponsaid blades to provide contact pressure between said blades and saidstuds when said blades are in contact with said rupture stud.

l1. In an electric switch, a terminal contact stud and a rupture contactstud spaced therefrom, a pair of contact blades pivotally mounted at oneend thereof on said terminal stud for releasable contact engagement atthe other end thereof with the opposite sides, respectively, of saidrupture stud, said blades being free to converge at said other endthereof `vhen disengaged from said rupture stud, said studs being ofsubstantially the same thickness,

vmeans,interengaging said blades between the ends ,thereof to limit theseparation-thereof'upon engagement with said rupture contact, to adistance which is less than the vthicknessof said studs and said bladesbeing formed of resilient material to provide contact pressure betweensaid blades and said studs when said blades are in contact with saidrupture stud.

12. In an electric switch, a terminal contact stud and a rupture contactstud spaced therefrom, a pair of contact blades having wide facesengageable with the opposite sides of said studs, respectively, a pivotextending through said blades and through said terminal contact studperpendicular-to the wide faces of said blades, and a member extendingalong a line `parallel to said pivot and intermediate the ends of theblades, said member extending loosely through at least one of saidblades and having restraining means limiting the separation of saidblades upon engagement thereof with said rupture contact, saidrestraining means including an abutment of said one of said -bladesremote from the other of said blades, said blades being free to convergeat the end thereof remote from said pivot when disengaged Yfrom saidrupture stud.

13. In an electric switch, a terminal contact stud and a rupture contactstud spaced therefrom, a pair of contact blades having Wide facesengageable with the opposite sides of said studs, respectively, a pivotextending through said blades and through said terminal contact studperpendicular .to the wide faces of said blades, a ymember extendingalong a line parallel to said pivot and interme- -diate the ends of theblades, said member extending lloosely through at least one of saidblades and Vhaving restraining means limiting the separation of saidblades upon engagement thereof with said rupture Contact, saidrestraining means including an abutment of said one of said bladesremote from the other of said blades, said blades being free to convergeat the end thereof remote from said pivot when disengaged from saidrupture stud, anda spring confined .between said one of said blades andsaid abutment arranged to ,act directly on said one of said bladesagainst both said studs, said spring having a vof said blades to provideresilient contact pressure ,on-both side Vblades against both saidstuds, said spring having ,a vhigh spring Vconstant and beingproportioned for release of ,contact pressure of said .blades againstboth said studs .as the ,direct lresult of said relativelymovable-blades being removed from said stationary rupture stud.

14. lIn an electric switch, a terminal contact stud and a rupturecontact stud spaced therefrom, a pair of v`contact blades having widefaces lengageable with the opposite sides of said contact studs,respectively, a ;pivot-,extending through said yblades and through `saidterminal contact stud perpendicular to the wide faces -of said blades, amember extending .along a line parallel to -said pivotand intermediatethe ends of lthe blades, said member extending loosely through both saidblades and having an abutment at -the face of each of said blades remotefromthe other ,of said blades `for limiting the separation of saidblades uponengagementtherewith with said lrupture contact, said bladesbeing free-to converge attheend thereof remote from said pivot whendisengaged from vsaid :rupture,:and.a leaf spring confined between oneof said abutmentsand-the faceof the blade nearest thereto, Said leafspringfextending along said -blade in opposite directions Yfromsaidabutment for biasing both ends of each tblade against Y,the :respectivecontact studs.

References Cited in the le of this -patent UNITED STATES PATENTS 670,145Bossert Mar. 19, 1901 1,880,734 Boll et al Oct. "4, 1932 v1,929,049Austin Oct. 3, '1933 2,009,815 Powers Tuly 30, 1935 2,186,476 Debby Jan.9, 1940 2,278,057 Borza Mar. 3-1, 1942 2,660,648 Luebkert Nov, 24, 19532,660,649 Luebkert Nov. 2'4, 1953 FOREIGN PATENTS 216,276 Germany Nov.15, 1909

